Not only… but also is an example of a correlative conjunction. We use it to present two pieces of information that are not only related but also unexpected. (See what we did there?!) Read on to learn how to correctly use not only… but also in your writing.
When to Use “Not Only… But Also”
Correlative conjunctions like not only… but also are pairs of words or phrases that link two elements of equal importance in a sentence. Other familiar examples of correlative conjunctions are either… or and neither… nor. You would use not only… but also when both of the related elements are somewhat unexpected or surprising:
I not only read the book but also saw the movie.
I not only visited the Eiffel Tower, but I also went to the Louvre.
We ate not only the biscuits but also half the donuts.
“Not Only… But Also”: The Rules
The phrases after not only and but also should follow the same structure. The above examples are correct because in the first two, we used verbs (read and saw, and visited and went). In the third example, not only and but also are both followed by noun phrases (the biscuits and half the donuts).
If we had structured the two parts differently, they would be wrong:
I not only enjoyed the book but also the movie. ✘
Here we have a verb (enjoyed) after not only and a noun phrase (the movie) after but also.
We ate not only the biscuits but also devoured half the donuts. ✘
This example is also incorrect because not only is followed by a noun phrase, while but also is followed by a verb. A simple way to check if you’ve structured not only… but also correctly is to connect the words that appear on either side of not only and but also with the word and. When you do this, they should read as a grammatically correct sentence.
Beginning a Clause With “Not Only… But Also”
When you start a clause or a sentence with not only, the subject and verb after not only must be swapped around (inverted) like this:
Not only was the coffee weak, but also it was cold. ✔
But you mustn’t change the order for the but also part:
Not only was the coffee weak, but also was it cold. ✘
Does “Not Only… But Also” Need a Comma?
Not only… but also doesn’t usually require a comma, especially if you’re using it to connect nouns or noun phrases. However, you should add a comma when you’re linking two independent clauses:
Not only did I pass the test, but I also got the highest score in my class.
Because the two clauses could each stand alone as a sentence, they should be separated by a comma.
Summary: Not Only… But Also
We hope you now feel confident about using not only… but also in your writing. For more grammar tips, check out our blog. And if you’d like an expert to check your writing for errors, we’re here to help. Not only do we return most documents within 24 hours, but we’ll also proofread the first 500 words for free.